[viraptor]

> will end up asking for more items in the build-matrix, and the CI time will balloon up again.

I don't think is has to end like that. You can have separate queues and separate levels of assurance. For example, does every commit have to be tested in each of 20 possible configs? You can run one common config by default and allow unblocking the rest on demand. Then enforce all of them only as a merge gate.

If you can also split them into separate queues that don't block each other, you get both larger matrix and faster dev turnaround.

[carreau]

Sure, and you are proving my point. You have to allocate time for someone to reply to all those questions and update the CI to only test what's necessary, or prioritize some test, and run the rest only if they pass etc.

So you do need policies to actually be allowed to optimise CI.